AVINASHBVN13007

MORPHOLOGYOF RED BLOOD

CELL.Erythrocytes

INTRODUCTION:- Red cell morphology can be defined as the

appearance of the erythrocytes on a Giemsa stained smear.

Careful examination of the red cells for the purpose of identifying abnormalities is part of the differential procedure.

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Why? Differentiating normal morphology from

abnormal and artificial morphology. Provide valuable diagnostic information to

the physician, Provide a quality control mechanism to

verify red cell indices values as determined by automated or manual methods.

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How:- Assess RBC morphology by examining the

smear in the feathered (thinner) edge where the RBC are randomly distributed and, for the most part, lie singly, with occasional doublets.

This area is referred to as the "critical area."

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How:- If the area is too thin, the red cells will

appear flat and somewhat square (cobblestone effect) with no central pallor.

If the area examined is too thick, the cells will be too close together to evaluate the morphology of individual cells.

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How To begin the red cell morphology

examination, use the low power (10X) objective to locate the "critical area."

The oil immersion objective (100X) is used for the actual evaluation.

FUNCTIONAL MORPHOLOGY. Like other cells

bounded by cell membrane but Non-Nucleated.

Cytoplasm contains pigmented protein – Haemoglobin

It is Chromoprotein – colour giving protein.

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NORMAL SIZE Diameter – 4.1-7.5 μm Thickness – 2 μm at

periphery & 1 μm at center Surface area – 57-140 μm2

Lowest in Goat

Highest in Man

Volume - 80 μm3 (78-86)

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Diameter of RBC in various species:-

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Species Size (μm)

GOAT 4.1

SHEEP 5.0

CATTLE & HORSE 5.6

PIG 6.2

CAT 6.5

DOG 7.3

MAN 7.5

NORMAL SHAPE Circular, biconcave disc. Advantages of biconcave shape –

Flexible , capillaries minimum diameter – 3.5 μm.

Greater surface area Can withstand changes of osmotic

pressure Allow easy exchange of O2 & CO2 &

rapid diffusion of other substances.

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SHAPE OF RBC ACCORDING TO DIFFERENT SPECIES :- DOG :- Cells are large (7.3microns),uniform in

size and have central pallor (biconcave disc). COW:- Average diameter is 5.6-6 microns .

Red cells may appear flat disc with little or no central depression (no central pallor).

SHEEP:- Average diameter 5.0 microns ,flat disc ,with little central depression

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Cont… CAT:- Cells average 6.5 microns in

diameter ,Shallow concaving ,only very slight central pallor , slight anisocyte (variation in size of RBC) . Up to 1 % of the cells may contain Howell-jolly bodies(nuclear remnants ) .

HORSE:- Erythrocyte have rouleaux formation, Shallow concaving ,Average diameter 5.6 microns ,uniform in size no central pallor .

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CAT HORSE

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Cont… GOAT:-  Erythrocyte are the smallest 4

microns and most variables in shape ,very shallow or flate surfaced RBC.

CAMEL :- Erythrocytes normal elliptical in shape and lake of cental depression .

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CAMEL

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Cont… DEER:- Sickle shaped.

POULTRY ( COLD BLOODED ANIMALS):- Amphibians and birds have mature erythrocyte is elliptical cell with an elliptical central nucleus .

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DEER BIRDS

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Erythrocyte Indices

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RED CELL INDICES Mean corpuscular

volume Mean corpuscular

Haemoglobin Mean corpuscular

haemoglobin concentration.

Colour index.

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MEAN CORPUSCULAR VOLUME Average volume of single red blood

cell. MCV = PCV x 10

--------------

RBC count/mm3

= 45X10/5 = 90 μm3

Normal value 78-94 μm3

Decreased in Microcytosis

Increased in Macrocytosis

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MEAN CORPUSCULAR HAEMOGLOBIN

Average weight of haemoglobin in each RBC MCH = Hb gm% X 10

-----------------

RBC count/mm3

= 15X10/5X1012 = 30 pg

normal range – 27-33 pg

Increases – Spherocytosis & megaloblastic anaemia

Decreases - anaemia

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MEAN CORPUSCULAR HAEMOGLOBIN CONCENTRATION.

Amount of Hb expressed as percentage of the volume of RBC.

MCHC = Hb gm%

------------------- X 100

PCV/100ml

= 15/45 X 100 = 33.3%

Normal value – 30-33%Decreases – Iron deficiency anaemia

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COLOUR INDEX. Ratio of Haemoglobin to RBC

CI = % of normal Hb

---------------------

% of normal RBC count

= 100/100 = 1

Normal range= 0.85-1.15Insignificant

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REFRENCES:- VETERINARY CLINICAL PATHOLOGY

4TH EDITION

EMBERT H. COLES

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Thank You